Monitoring Network Instrumentation
All Instruments

The UV-B Monitoring and Research Program operates a national network of solar irradiance monitoring stations equipped with instruments which provide measurements to meet the needs of both agricultural and atmospheric researchers. Two of the instruments deployed in the network are unique since they provide the important and useful direct component of solar irradiance without the expense and complexity of a solar tracker. Our instrumentation includes:

  1. Multifilter Rotating Shadowband Radiometer: Direct, Total Horizontal and Diffuse Visible Irradiance at nominal 415, 500, 615, 673, 870, 940 nano-meter wavelengths, plus one unfiltered (open) silicon photodiode of 300-1040 nm.
  2. Broadband UVB-1 Pyranometer: (280-320 nm, erythemal weighted for skin damage)
  3. Photosynthetically Active Radiation Sensor: 400 - 700 nano-meter wavelengths
  4. Ultraviolet Multifilter Rotating Shadowband Radiometer: Direct, Total Horizontal, and Diffuse UV Irradiance at nominal 300, 305, 311, 317, 325, 332 and 368 nano-meter wavelengths
  5. Surface Reflectance, Downward Looking Photometer
  6. Air Temperature
  7. Relative Humidity Sensor
  8. Barometric Pressure Sensor, some sites
  9. UV-A biometer, a few sites

Electormagnetic Coverage

All instruments have on-board data logging capability. Measurements are provided as 3-minute averages, aggregated from 15/20 second readings of each instruments' raw output voltage. Our instruments and support equipment receive periodic on-site servicing and maintenance. Measurements are scrutinized both automatically and manually by program staff daily. Trained on-site technicians service and maintain field instruments weekly, and are available to respond quickly to requests for problem resolution. These measures result in the collection of high quality data with very good capture rates. Data and data products are available for download in numeric or graphic format from our Download section.

Originally, at the time of the USDA's workshops(1991 and 1992), the primary instrument available for measuring UV radiation was a broadband-type pyranometer, shown as instruments 2 and 9 above. Such instruments only measure global (or total) irradiance, which includes both the direct rays from the Sun as well as the diffuse rays as scattered by clouds and other atrospheric constituents. What was needed in addition was the ability to measure the direct and diffuse components separately and directly, as this facilitates measurement of the turbidity of the atmosphere due to aerosols and other contaminants. Fortunately, a new type of instrument, the Multifilter Rotating Shadowband Radiometer (MFRSR) had just been developed by scientists at Battelle Laboratories in Washington State. The capacity to manufacture these instruments was awarded to Yankee Environmental Services (YES) of Turners Falls, Massachusetts. The MFRSR is equipped with a shadowband that enables the separation and measurement of the total (global), diffuse horizontal, and direct normal components of solar irradiance (as depicted below) within a single instrument. This capability to inexpensively and reliably capture the direct component has a side benefit, in that it allows for periodic in-situ calibration checks of the instruments using the Sun as a source [the Langley method], independent of the laboratory calibration (Slusser, et al., 2000).

Sunny day